1. Field of the Invention
This invention relates generally to the field of encasement or encapsulation of structural members, and more particularly to the encasement or encapsulation of structural members partially submerged in either fresh water or salt water.
2. Background of the Invention
The use of piles or piers as structural supports for wharfs, bridges and other marine environment structures is well known. The usual materials of construction for such marine structures are concrete, steel, wood or a combination or composite of two or more of these materials. All of the aforementioned materials of construction are vulnerable to deterioration. In particular, wooden pilings have been used for many years to support piers, wharfs, boat slips, and in some instances older bridges. It is well known that such piling is subject to many hazards necessitating the replacement of same. One major source of damage which drastically shortens the life expectancy of wood piling is the attack on the piling by certain marine parasites and microorganisms. These marine microorganisms feed upon the cellulose material of the wood piling extracting a food substance of a polysaccharide carbohydrate nature.
Particular marine microorganisms known to attack wooden pilings include limnoria, gribbles and teredo microorganisms. The teredo begins life as a larva and begins its metamorphosis into an adult when it has attached itself to the surface of a piece of submerged timber. The teredo will begin burrowing into the submerged timber and its tail appendage will seal off the entry way. The only visible presence of a teredo is the occurrence of two microscopic syphon tubes, one for the inhalation of fresh water and the other for exhalation. In its boring, the toredo will dispose of waste through the exhalation syphon and the inhalation syphon is designed to produce continuously circulating water over the toredo's gills for the absorption of oxygen. New larva is also disposed of through the exhalation syphon to infest the same submerged timber or other timber. The specific danger with the toredo is that the submerged timber pile appears to be secure and intact, when in fact, the interior of the pile may contain a great deal of infestation thus weakening the pile.
The second marine borer, of the limnoria species, which is sometimes referred to as a gribble, resembles lice and is about the size of a small ant and it is capable of boring holes of approximately 3 mm in diameter. The limnoria rarely penetrate the timber for more than 10 to 12 millimeters, but they normally infest in great numbers on the outer layer of the submerged timber such that the submerged timber takes on a honeycombed appearance with tiny individual channels. This attack combined with the eroding effects of the sea's tide will break down the surface of the wood and expose new surfaces for attack.
Previous efforts to safeguard these hazards include the impregnation of the structures and/or the coating of their surfaces with special preservatives and protective coatings using materials such as creosote, tar and impervious paints. While these materials do cover certain hazards, they are in ineffective with respect to others and the chemical treatments are subject to leeching, scaling and erosion by the action of the constantly moving surrounding water, taken together with temperature changes and shock forces. Further, the high salinity and other constituents of sea water also contribute to degradation of these protective measures.
Various guard devices have been proposed for installation about pilings to solve the infestation problem. One prior art protective measure involved enclosing portions of the piling in direct contact with the water with a sheet of plastic by wrapping the sheet tightly around the pile. The piling has also been encased with rigid polyvinyl chloride tubing. This method attempts to provide a barrier to access by marine life not readily present in or on the piling and traps that marine life present in and on the pilings inside the jacket. The intent of the wrapping is to trap a thin layer of water between the wrapping and the wooden pile and to prevent that thin film from being refreshened by fresh sea water. This water, becoming stagnate, is rapidly depleted of oxygen and thus deprives the marine life of the vital gas and arrests further damage to the piling. The Applicant has found while this preventative measure works in theory, in actual practice, a great majority of the wraps do not prevent the refreshening of the water trapped between the wrapping and the pile and thus the infestation continues.
Bell, in U.S. Pat. No. 4,983,072 proposed a method of protecting submerged pilings in which the wrap was enhanced by filing the space between the wrap and the piling with a water insoluble filler material, comprised of either sand or silt. While this process may enhance the deprivation of oxygen to the marine infestation, it is cumbersome and if the wrap is penetrated, the sand or silt may be washed away from the piling.
Applicant's invention is directed towards an apparatus and method in the form of a combination wrap and marine acceptable filler composite which can be pumped within the wrap in aerosol form and which solidifies to fill the gap between the wrap and the piling and also fill in any gaps in the piling caused by the aforementioned marine borers.